Microwave plasmas are employed in technical fields such as, for example, the manufacture or processing of components, in microelectronics, during coating, in the decomposition of gases, synthesis or cleaning of materials.
In the devices, the microwaves are fed by means of coupling points into the plasma chamber, together with the container, i.e. working space, which it may optionally contain, from a microwave generator optionally via a feed to a waveguide resonator around the plasma chamber. It is customary, in particular, to use ring resonators, i.e. waveguide resonators which are designed as a ring and have a short length along their axis in comparison with the relatively large cross-sectional diameter of the resonator ring. It is common for the axis of the ring resonator and the axis of the plasma chamber, in this case for example designed as a tube, to have the same or a common z axis.
According to DE 196 00 223.0-33, the resonator ring has a rectangular cross-section, and the coupling points are, for example, in the form of slots in the short cross-sectional side. Devices of this type for the production of microwave plasmas have high efficiency. However, there is a need for more uniform and more powerful plasma chambers and more simply configured devices.